Leveraging Actual Cable Network Usage

ABSTRACT

Determining a bit rate at which to deliver a packet stream over a network link. An origin device transmits over the network link unsolicited data packets to a destination device while contemporaneously transmitting over the network link a first packet stream encoded at an initial bit rate to the destination device. The origin device may be, but need not be, a content delivery network (CDN) edge node and the destination device may be, but need not be, a cable modem (CM). The origin device determines whether the network link supports delivering a second packet stream in lieu of the first packet stream encoded at a higher bit rate based, at least in part, on an amount of retransmission requests the origin device receives for packets in the first packet stream from the destination device.

CLAIM OF PRIORITY

This application claims priority to U.S. Provisional Patent ApplicationSer. No. 62/992,419, filed Mar. 20, 2020, entitled “Understanding andLeveraging Actual Cable Network Usage,” the entire contents of which arehereby incorporated by reference for all purposes as if fully set forthherein.

FIELD OF THE INVENTION

Embodiments of the invention relate to determining actual useablebandwidth of a network link.

BACKGROUND

Many technologies, particularly those involved in the transmission ofvideo and audio data, are required to optimize the bit rate at which adata packet stream is transmitted over a network link to provide thebest possible quality of experience for the end user. At present, knownapproaches for selecting an optimal bit rate for transmitting a packetstream over a particular network link are simplistic. Such approachesoften fail to properly model the real-world behavior of a network, asaccurately capturing the nuance of network behavior is difficult and isprone to error.

Digital video is typically delivered over a packet-based network using aContent Delivery Network (CDN), such as a cable provider. In a CDN, anorigin or headend server is responsible for producing or supplying videocontent, which may be delivered across the network to clients thatrequested the video content. When a particular geographical region hasenough clients connecting to the CDN, an edge server is often deployedto assist with providing service to that geographical region. The roleof the edge server is to receive requests from clients in that regionand redirect those requests to the headend server of the CDN. Whileclients in a region may send multiple requests for the same videocontent, the edge server need only send one request for the videocontent to the headend server; once the edge server possess therequested video content from the headend server, the edge server maydeliver the video content to any client that requests the video contentin the geographical region for which the edge server is responsible.This approach thus has the advantage of saving bandwidth within the CDNbetween the headend and the edge servers.

A CDN may be implemented as a Converged Cable Access Platform (CCAP),which is an industry standard platform for transmitting video data andaudio content. The CCAP platform is specified by CableLabs ofLouisville, Colorado. CableLabs has publicly issued a Remote PHY familyof specifications, known as the MHAv2 specifications (Modular HeadendArchitecture version 2). The MHAv2 specifications describe how a CCAPplatform may be separated into two components, (1) a CCAP Core locatedat the cable headend, and (2) a Remote PHY device (RPD), which istypically located outdoors. An RPD may be located, for example, at thejunction of the fiber and coax plants in an optical node serving as aRemote PHY Node (RPN).

FIG. 1 is a block diagram of an exemplary CCAP system which includes anRPD situated inside an RPN in accordance with the MHAv2 specificationsof the prior art. The RPD of FIG. 1 communicates over a digital fibernetwork using Ethernet/IP to other networking devices “upstream” (i.e.,in the direction from the RPD to the CCAP Core). In the “downstream”direction (i.e., in the direction from the RPD to a Data Over CableService Interface Specification (DOCSIS) cable modem), the RPD modulatesinformation streams (data, video, voice, etc.) into radio frequency (RF)signals that are carried over coaxial cables and demodulates similarsuch streams from received RF signals.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention are illustrated by way of example, and notby way of limitation, in the figures of the accompanying drawings and inwhich like reference numerals refer to similar elements and in which:

FIG. 1 is a block diagram of a CCAP system which includes a Remote PHYnode (RPN) in accordance with the MHAv2 specifications of the prior art;

FIG. 2 is a block diagram of a content delivery network (CDN) edge nodetransmitting a data packet stream to a customer premises equipment (CPE)in accordance with an embodiment of the invention;

FIG. 3 is a flowchart illustrating the functional steps of determining abit rate at which to deliver a packet stream over a network link inaccordance with an embodiment of the invention; and

FIG. 4 is a block diagram of a computer system that may correspond to anorigin device or a destination device shown in FIG. 2 in accordance withan embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Approaches for determining an optimal bit rate at which to deliver apacket stream over a network link based on observed network conditionsare presented herein. In the following description, for the purposes ofexplanation, numerous specific details are set forth to provide athorough understanding of the embodiments of the invention describedherein. It will be apparent, however, that the embodiments of theinvention described herein may be practiced without these specificdetails. In other instances, well-known structures and devices are shownin block diagram form or discussed at a high level to avoid obscuringteachings of embodiments of the invention.

Embodiments of the invention enable a node, such as but not limited to aContent Delivery Network (CDN) edge node, to identify at what bit rate adata packet stream should be delivered over a network link to adestination device, such as a Cable Modem (CM), based on observedconditions of that network link. Embodiments may be used to carry outvideo bit rate selection in an adaptive bit rate streaming protocol suchas HTTP Live Streaming (HLS) or Dynamic Adaptive Streaming over HTTP(DASH). Embodiments preserve a user's quality of experience in using thedata packet stream while continuing to observe the impact on thebandwidth of the network link resulting from transmitting the datapacket stream at a higher bit rate. Embodiments may be implementedentirely at the node sending the packet stream over the network linkwithout requiring or involving a custom client at the destination.

As an example of a context in which embodiments of the invention may beemployed, consider FIG. 2, which is a block diagram of origin device 210transmitting a data packet stream to destination device 220 over networklink 230 in accordance with an embodiment of the invention. Origindevice 210, as broadly used herein, represents any computer systemcapable of sending a stream of packets over network link 230.Destination device 220, as broadly used herein, represents any computersystem capable of receiving a stream of packets over network link 230.

Origin device 210 and destination device 220 may be implemented in avariety of different contexts, such as a Content Delivery Network (CDN).For example, origin device 210 may correspond to a CDN Edge Node whiledestination device 220 may correspond to a Cable Modem (CM). As anotherexample, origin device 210 may correspond to a server that operates at acable headend and destination device 220 may correspond to CDN edgenode.

Network link 230, as broadly used herein, represents any mechanism forexchanging data packets between origin device 210 and destination device220. Network link 230 may be implemented, for example, by a wirelessnetwork or by a wired network. The exchange of data packets over networklink 230 may be performed using a variety of different protocols,including without limitation Transmission Control Protocol (TCP) andUser Datagram Protocol (UDP). To provide a concrete example, networklink 230 may be implemented using a TCP connection that extends over atleast ‘the last mile network’ to a cable customer device (i.e., customerpremises equipment or (CPE)).

The effective bandwidth available to network link 230 will fluctuateover time for various reasons. For example, effective bandwidthavailable to network link 230 will vary based on network connectionscarried at any given time over network link 230. As another example,within a user's residence, radio interference can degrade the connectionbetween the user's device consuming the video stream and any Wi-Firouter used by the user. Other sources of intermittent noise andinterference in the field can degrade the available bandwidth on networklink 230.

FIG. 3 is a flowchart illustrating the functional steps of determining abit rate at which to deliver a packet stream over a network link inaccordance with an embodiment of the invention. The steps of FIG. 3 aredesigned to select or identify the highest bit rate at which to send apacket stream over network link 230 that is currently deemedsustainable. The objective is not simply to deliver the highest bit ratethat is possible over network link 230, but rather, the objective is tomaximize the user's quality of experience with the delivered packetstream. While it is true that delivering a video stream at a higher bitrate can result in a greater perceived picture quality for the viewer,the inverse can also be true. For example, increasing the bit rate of avideo stream beyond what can be safely supported by the presentoperational conditions of a network link can lead to video stalling(which may occur when a video decoder is starved for bits to play when aselected bit rate is too high) and/or frequent switching of bit rates.In both cases, the user may perceive a shift, transition, or disruptionin picture quality, which can result in a lower overall quality ofexperience than if the higher picture quality video was never deliveredin the first place. Advantageously, embodiments preserve a user'squality of experience in using the data packet stream while continuingto observe the impact on the bandwidth of the network link resultingfrom transmitting the data packet stream at a higher bit rate; thus, theuser's quality of experience is maximized in accordance with actualobserved conditions on network link 230.

Returning to the steps of FIG. 3, in step 310, origin device 210transmits over network link 230 unsolicited data packets to destinationdevice 220 while contemporaneously transmitting over network link 230 afirst packet stream encoded at an initial bit rate to destination device220. The first packet stream represents the packet stream in which theuser's quality of experience in using is desired to be optimized in asustainable manner over network link 230. For example, the first packetstream may correspond to a digital video or digital content requestedfrom a CDN or a video stream associated with an application, such asvideo conference software.

The unsolicited data packets may correspond to unsolicitedretransmission packets per a variety of transport protocols, such as butnot limited to Transmission Control Protocol (TCP) and User DatagramProtocol (UDP). The purpose of sending the unsolicited data packets isso the actual bandwidth presently available to network link 230 may beevaluated and ascertained by origin device 210. The unsolicited datapackets will be dropped by the recipient client at destination device220 if the unsolicited data packets are unneeded. It is intended thatthe majority of these unsolicited data packets will not be needed, asthey are intended to only consume a portion of the bandwidth presentlyavailable to network link 230.

In step 320, origin device 210 determines whether the present state ofnetwork link 230 supports delivering a second packet stream in lieu ofthe first packet stream. The second packet stream may correspond to adifferent version of the first packet stream encoded at a new bit rate.This determination may be made solely at origin device 210 based on thenumber of retransmission requests received by origin device 210 forpackets not received by destination device 220. In this way, if theamount of unsolicited data packets sent by origin device 210 todestination device 220 over network link 230 causes network link 230 todrop certain packets expected by destination device 220 beyond anacceptable threshold, then origin device 210 can ascertain the amount ofavailable bandwidth presently available to network link 230 does notsupport transmitting content at a higher bit rate at present.

Embodiments may increase or decrease the amount of unsolicited datapackets as needed over time until the present available bandwidthavailable to network link 230 is ascertained to a certain level ofconfidence. This process may be repeated periodically over time tocontinually monitor the present available bandwidth available to networklink 230.

Embodiments of the invention enable a variety of different applications.For example, the steps of FIG. 3 may be used to improve human generatedclient or server-side bit rate optimizations for encoding, transcoding,or transmitting packet streams. As another example, the steps of FIG. 3may be used to gather training data for artificial intelligence clientor server-side bit rate optimizations for encoding, transcoding, ortransmitting packet streams.

Embodiments may be used to improve the quality of software displayingvideo streams to one or more users. For example, in an embodiment,origin device 210 and destination device 220 may be computer systemsthat both execute video conference software. The video conferencesoftware executing on origin device 210 and destination device 220 maybe hosting a video call. The video conference software may determine fordestination device 210, using an embodiment, a new bit rate to use intransmitting video streams over network link 230 to destination device220.

U.S. patent application Ser. No. 16/798,940 (the '940 application), wasfiled on Feb. 24, 2020, is entitled Automatic OFDM Profile Selection,and the entire contents of which are hereby incorporated by referencefor all purposes as if fully set forth herein. This applicationdiscusses approaches for selecting an appropriate DOCSIS profile for anorthogonal frequency-division multiplexing (OFDM) channel. Embodimentsof the invention may employ the modulation profile assignment techniquesdiscussed in the '940 application to selecting an appropriate DOCSISprofile identifying a new bit rate identified by the steps of FIG. 3 foran orthogonal frequency-division multiplexing (OFDM) channel.

FIG. 4 is a block diagram of a computer system that may correspond to anorigin device 210 or a destination device 220 shown in FIG. 2 inaccordance with an embodiment of the invention. In an embodiment,computer system 400 includes processor 404, main memory 406, ROM 408,storage device 410, and communication interface 418. Computer system 400includes at least one processor 404 for processing information. Computersystem 400 also includes a main memory 406, such as a random-accessmemory (RAM) or other dynamic storage device, for storing informationand instructions to be executed by processor 404. Main memory 406 alsomay be used for storing temporary variables or other intermediateinformation during execution of instructions to be executed by processor404. Computer system 400 further includes a read only memory (ROM) 408or other static storage device for storing static information andinstructions for processor 404. A storage device 410, such as a magneticdisk or optical disk, is provided for storing information andinstructions.

Embodiments of the invention are related to the use of computer system400 for implementing the techniques described herein. According to oneembodiment of the invention, those techniques are performed by computersystem 400 in response to processor 404 executing one or more sequencesof one or more instructions contained in main memory 406. Suchinstructions may be read into main memory 406 from anothermachine-readable medium, such as storage device 410. Execution of thesequences of instructions contained in main memory 406 causes processor404 to perform the process steps described herein. In alternativeembodiments, hard-wired circuitry may be used in place of or incombination with software instructions to implement embodiments of theinvention. Thus, embodiments of the invention are not limited to anyspecific combination of hardware circuitry and software.

The term “non-transitory computer-readable storage medium” as usedherein refers to any tangible medium that participates in storinginstructions which may be provided to processor 404 for execution.Non-limiting, illustrative examples of non-transitory machine-readablemedia include, for example, a floppy disk, a flexible disk, hard disk,magnetic tape, or any other magnetic medium, a CD-ROM, any other opticalmedium, a RAM, a PROM, and EPROM, a FLASH-EPROM, any other memory chipor cartridge, or any other medium from which a computer can read.

Various forms of non-transitory computer -readable media may be involvedin carrying one or more sequences of one or more instructions toprocessor 404 for execution. For example, the instructions may initiallybe carried on a magnetic disk of a remote computer. The remote computercan load the instructions into its dynamic memory and send theinstructions over a network link 420 to computer system 400.

Communication interface 418 provides a two-way data communicationcoupling to a network link 420 that is connected to a local network. Forexample, communication interface 418 may be an integrated servicesdigital network (ISDN) card or a modem to provide a data communicationconnection to a corresponding type of telephone line. As anotherexample, communication interface 418 may be a local area network (LAN)card to provide a data communication connection to a compatible LAN.Wireless links may also be implemented. In any such implementation,communication interface 418 sends and receives electrical,electromagnetic, or optical signals that carry digital data streamsrepresenting various types of information.

Network link 420 typically provides data communication through one ormore networks to other data devices. For example, network link 420 mayprovide a connection through a local network to a host computer or todata equipment operated by an Internet Service Provider (ISP).

Computer system 400 can send messages and receive data, includingprogram code, through the network(s), network link 420 and communicationinterface 418. For example, a server might transmit a requested code foran application program through the Internet, a local ISP, a localnetwork, subsequently to communication interface 418. The received codemay be executed by processor 404 as it is received, and/or stored instorage device 410, or other non-volatile storage for later execution.

In the foregoing specification, embodiments of the invention have beendescribed with reference to numerous specific details that may vary fromimplementation to implementation. Thus, the sole and exclusive indicatorof what is the invention and is intended by the applicants to be theinvention, is the set of claims that issue from this application, in thespecific form in which such claims issue, including any subsequentcorrection. Any definitions expressly set forth herein for termscontained in such claims shall govern the meaning of such terms as usedin the claims. Hence, no limitation, element, property, feature,advantage, or attribute that is not expressly recited in a claim shouldlimit the scope of such claim in any way. The specification and drawingsare, accordingly, to be regarded in an illustrative rather than arestrictive sense.

What is claimed is:
 1. A non-transitory computer-readable storage medium storing one or more sequences of instructions, which when executed by one or more processors, cause: determining a bit rate at which to deliver a packet stream over a network link: (a) an origin device transmitting over the network link unsolicited data packets to a destination device while contemporaneously transmitting over the network link a first packet stream encoded at an initial bit rate to the destination device, and (b) the origin device determining whether the network link supports delivering a second packet stream in lieu of said first packet stream, wherein said second packet stream is encoded at a new bit rate, higher than said initial bit rate, which is based on an amount of retransmission requests the origin device receives for packets in said first packet stream from said destination device.
 2. The non-transitory computer-readable storage medium of claim 1, wherein said origin device is a content delivery network (CDN) edge node, and wherein said destination device is a cable modem (CM).
 3. The non-transitory computer-readable storage medium of claim 1, wherein said origin device operates at a cable headend, and wherein said destination device is a content delivery network (CDN) edge node.
 4. The non-transitory computer-readable storage medium of claim 1, wherein said origin device and said destination device both execute video conference software, and wherein said video conference software determines, for said destination device, the new bit rate, and wherein the new bit rate is employed by said video conference software in transmitting video streams over said network link to said destination device.
 5. The non-transitory computer-readable storage medium of claim 1, wherein said first packet stream is transmitted using one or more of Transmission Control Protocol (TCP) and User Datagram Protocol (UDP).
 6. An apparatus for determining a bit rate at which to deliver a packet stream over a network link, comprising: one or more processors; and one or more non-transitory computer-readable storage mediums storing one or more sequences of instructions, which when executed, cause: an origin device transmitting over the network link unsolicited data packets to a destination device while contemporaneously transmitting over the network link a first packet stream encoded at an initial bit rate to the destination device, and the origin device determining whether the network link supports delivering a second packet stream in lieu of said first packet stream, wherein said second packet stream is encoded at a new bit rate, higher than said initial bit rate, which is based on an amount of retransmission requests the origin device receives for packets in said first packet stream from said destination device.
 7. The apparatus of claim 6, wherein said origin device is a content delivery network (CDN) edge node, and wherein said destination device is a cable modem (CM).
 8. The apparatus of claim 6, wherein said origin device operates at a cable headend, and wherein said destination device is a content delivery network (CDN) edge node.
 9. The apparatus of claim 6, wherein said origin device and said destination device both execute video conference software, and wherein said video conference software determines, for said destination device, the new bit rate, and wherein the new bit rate is employed by said video conference software in transmitting video streams over said network link to said destination device.
 10. The apparatus of claim 6, wherein said first packet stream is transmitted using one or more of Transmission Control Protocol (TCP) and User Datagram Protocol (UDP).
 11. A method for determining a bit rate at which to deliver a packet stream over a network link, comprising: an origin device transmitting over the network link unsolicited data packets to a destination device while contemporaneously transmitting over the network link a first packet stream encoded at an initial bit rate to the destination device, and the origin device determining whether the network link supports delivering a second packet stream in lieu of said first packet stream, wherein said second packet stream is encoded at a new bit rate, higher than said initial bit rate, which is based on an amount of retransmission requests the origin device receives for packets in said first packet stream from said destination device.
 12. The method of claim 11, wherein said origin device is a content delivery network (CDN) edge node, and wherein said destination device is a cable modem (CM).
 13. The method of claim 11, wherein said origin device operates at a cable headend, and wherein said destination device is a content delivery network (CDN) edge node.
 14. The method of claim 11, wherein said origin device and said destination device both execute video conference software, and wherein said video conference software determines, for said destination device, the new bit rate, and wherein the new bit rate is employed by said video conference software in transmitting video streams over said network link to said destination device.
 15. The method of claim 11, wherein said first packet stream is transmitted using one or more of Transmission Control Protocol (TCP) and User Datagram Protocol (UDP). 